The invention generally relates to networks and, more particularly, the invention relates to multicast traffic across a computer network.
Multicasting is a known method of transmitting information to selected groups of users across a network, such as the Internet. For example, the transmission of an E-mail message to a group of users, each user being listed on a mailing list, uses multicasting principles. Video conferencing and teleconferencing also use multicasting principles and, accordingly, are often referred to as xe2x80x9cmulticonferencing.xe2x80x9d
Due to increased demand for uses utilizing multicasting principles, protocols such as the Internet Group Multicast Protocol (xe2x80x9cIGMPxe2x80x9d) have been developed and refined to support multicasting over a Transmission Control Protocol/Internet Protocol (xe2x80x9cTCP/IPxe2x80x9d) network, such as the Internet. The new protocols, such as IGMP, allow users to easily create and join multicasting sessions (xe2x80x9cmulticastsxe2x80x9d). Accordingly, the number of multicasts transmitted over a network have increased.
The increase in the number of multicasts results in an increase in the overhead needed to support multicasting. For example, Multicast Source Discover Protocol (xe2x80x9cMSDPxe2x80x9d) requires, in a Protocol Independent Multicast-Sparse Mode (xe2x80x9cPIM-SMxe2x80x9d) domain, a network device responsible for a particular multicast, referred to as a Rendezvous Point (xe2x80x9cRPxe2x80x9d) for the multicast, to peer with other RPs in the PIM-SM domain. As a result, all multicast messages sent to the PIM-SM domain are forwarded to all the RPs in the PIM-SM domain, regardless of whether the RP is responsible for the particular multicast referenced in the multicast message. Accordingly, an increase in the number of multicasts, as well as an increase in the number of RPs, results in an increase in the number of internal multicast messages in the PIM-SM domain.
Thus, a need exists for minimizing the overhead needed to support multicasting. In particular, a need exists for minimizing internal multicast traffic.
In accordance with one aspect of the invention, an apparatus and method of minimizing multicast traffic in a given multicast domain, the given multicast domain having a plurality of network devices, the plurality of network devices including at least one responsible network device, the responsible network device being responsible for at least one particular multicast traffic, configures a network device in the multicast domain to coordinate multicast messages sent to and from the multicast domain and generates a peering relationship between the configured network device and each responsible network device. The peering relationship ensures that a responsible network device receives multicast messages which reference its particular multicast traffic only.
In an alternate embodiment of the invention, the apparatus and method of minimizing multicast traffic in a given multicast domain receives at the configured network device a multicast message sent to the multicast domain and forwards the received multicast message to the responsible network device for the multicast traffic referenced in the received multicast message. In a further alternate embodiment of the invention, the apparatus and method of minimizing multicast traffic in a given multicast domain receives at the configured network device a multicast message sent from a responsible network device in the multicast domain and forwards the received multicast message to at least one other multicast domain.
In accordance with another embodiment of the invention, an apparatus and method of minimizing multicast traffic in a network is provided with the network having a given multicast domain, the given multicast domain having a plurality of network devices, the plurality of network devices including at least one responsible network device, and the responsible network device being responsible for at least one particular multicast traffic. In the embodiment, the apparatus and method configures a network device in the given multicast domain to coordinate multicast messages sent to and from the given multicast domain, generates a peering relationship between the configured network device and each responsible network device, the peering relationship ensuring that a responsible network device receives multicast messages which reference its particular multicast traffic only, sends a multicast message to the given multicast domain, receives the multicast message at the configured network device, and forwards the received multicast message to the responsible network device for the multicast traffic referenced in the received multicast message.
In an alternate embodiment of the invention, the apparatus and method of minimizing multicast traffic in a network generates a peering relationship between the configured network device and a network device in another multicast domain. In a further alternate embodiment of the invention, the apparatus and method of minimizing multicast traffic in a network receives at the configured network device a second multicast message sent from a responsible network device in the given multicast domain and forwards the received multicast message to the peered network device in the another multicast domain.
In another embodiment of the invention, the apparatus and method of minimizing multicast traffic in a given multicast domain, or in a network, constructs an information message that alerts network devices of the coordinating capabilities of the configured network device and forwards the information message to at least one network device. In one alternate embodiment of the invention, the information message is a part of a multicast protocol message. In a further embodiment of the invention, one or more bits in one or more fields of the multicast protocol message are set as alerts for the coordinating capabilities of the configured network device.
In alternate embodiments of the invention, the configured network device generates a peering relationship with all of the responsible network devices in the multicast domain, thereby coordinating all of the multicast messages in the multicast domain or, in the alternative, the configured network device generates a peering relationship with a subset of the responsible network devices in the multicast domain, thereby coordinating a subset of the multicast messages in the multicast domain.
In another alternate embodiment of the invention, the configured network device is also a responsible network device. In a further alternate embodiment of the invention, the given multicast domain is a protocol independent multicast domain. In a still further alternative embodiment of the invention, the given multicast domain is part of a Multicast Source Discovery Protocol backbone.